htools: split parts of HTools/Types.hs into BasicTypes.hs

The 'Result' type is common and:

- might be used outside of HTools-specific code too
- is better split as we need these basic types for building the more
  complex ones in Types.hs

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>